/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/
let a =new Promise((resolve) => {
  resolve('hello')
})
let b =new Promise((resolve) => {
  resolve('lagou')
})
let c =new Promise((resolve) => {
  resolve('I ♥ U')
})
Promise.all([a, b, c]).then((res) => {
  console.log(res[0]+res[1]+res[2])
})